Despite advancements in treatment, lung cancer remains a major cause of mortality in the world. Since lung cancer risk remains high for years after smoking cessation, new strategies are required to decrease lung cancer mortality either by early detection or through chemoprevention. However the efficiency of lung cancer chemoprevention trials is hampered by an inability to identify high risk subjects and difficulties in determining the success of intervention within a short time frame. The long term goal of this project is to identify and validate genotypic and phenotypic biomarkers which could be used to select high risk individuals for intervention and could be used as intermediate markers of response. Based on the premise that lung tumors represent a field cancerization phenomenon and undergo a multistep tumorigenesis process, we will identify biomarkers that will reflect the level of biological alteration in the lung field of individuals at risk for lung cancer. Our hypothesis is that those individuals harboring the greatest degree of genotypic and phenotypic abnormalities in their lung tissue will be at the highest risk of developing lung cancer. Genetic changes in the field will be explored on tissue sections using chromosome in situ hybridization (ISH), DNA content, and molecular allelotype, clonality, and sequencing assays to detect the degree of generalized genetic instability and extent of outgrowth of aberrant clones. Phenotypic changes in the lung field will be detected using immunocytochemical assays with antibodies and techniques that recognize dysregulation of proliferation (PCNA), growth regulation (EGFR, p53, TGF-beta, and cell loss mechanisms (end-labeling assays). The nature of the lung field at risk will be determined by an extensive biomarker examination of pneumonectomy and lobectomy specimens of lung primary tumor resections (i.e. "molecular Auerbach" analysis, Specific Aim 1). Identification of biomarkers which identify high risk lung tissue for second primary lung tumor development will be accomplished through retrospective analyses of "normal" tissue from first primary lung tumor specimens derived from individuals who subsequently did or did not develop a second lung primary (Specific Aim 2). The value of these informative biomarkers will be tested prospectively on normal lung tissue derived from the primary lung tumor resections of patients entering onto the chemoprevention trial of Project 1 (Specific Aim 3). Finally the use of these biomarkers as intermediate markers of response will be determined in bronchial biopsy specimens obtained from the placebo-controlled chemoprevention trial of Project 1 (Specific Aim 4). By the project's end, we will identify and validate genotype and phenotype biomarkers which will be useful for identifying the degree of lung tumor risk an responsiveness to intervention in lung cancer chemoprevention trials.